This invention is directed to a self-supporting grate for a drain structure. The self-supporting grate is designed such that a variable fluid flow through the grate, depending on the height of the fluid to be discharged through the grate is achieved. The variable rate is achieved by the use of a plurality of weirs sized and shaped so as to allow for variable flow rate depending on the depth of the fluid to be removed. A guard lip is located exterior of the weirs and serves to prevent debris from clogging said weirs.
Most flat topped roofs of buildings, houses and the like, as well as other structures such as parking lots and the like, incorporate grated drain structures for removal of fluid, i.e., water, from the flat area. The grate is incorporated on the drain structure to prevent foreign bodies from being deposited into the drain structure and clogging the draining system and the like. Further, the grates are designed to keep vermin and other such pests from entering or exiting from the drain system.
There presently exist a number of drain structures as, for example, the structure described in my U.S. Pat. No. 3,884,809. In this drain structure, a scupper drain is equipped with a self-supporting dome covering the entrance to the portion of the drain which serves to divert fluid from the top of the drain through the drain and into the drain pipe. For use on flat roofed buildings and the like, this type of drain has been found very utilitarian in ease of installation, longevity of the product and prevention of entry of foreign matter into the drain system.
Certain geographical areas are subjected to weather patterns such that within a very short period of time a considerable amount of rainfall occurs resulting in the production of a sizable amount of standing water on structures, paved areas and the like. Since building roofs and the like and parking lots and the like are covered with material impervious to water penetration, the rainfall accumulates on these surfaces at depths depending on the collecting area of the surface as well as the amount of rainfall.
Because of the inability of storm drain systems to handle a large amount of water over a specific time period, heavy rainfall may completely overtax the capacity of the storm drain system. In order to combat the problem of either inadequate storm drain capacity of a municipality and/or excessive rainfall over a short period of time, it would be beneficial to have the individual drain structures on each and every building, parking lot or the like be able to govern the influx of run-off into the storm drain system such that the storm drain system could operate at full capacity, but would not be overtaxed or overburdened such that erratic water removal and/or damage to the storm drain system resulted.
Many of the grates utilized on existing drain structures are generally of the type illustrated in the above noted patent. The noted patent utilizes a drain having a foraminous grate. This grate is formed by including a plurality of equally sized slots or openings in the grate. These slots or openings extend from an area adjacent to where the grate fits onto the scupper drain structure and up to and including the crown or uppermost periphery of the grate. In other grates, such as flat grates, the openings would be evenly spaced over the surface of the grate. It is obvious that with this type of grate system there can be no specificity with regard to flow rate of the water or other fluid through the grate. It is also obvious that such grates are susceptible to being clogged by solid material carried to their foraminous portions by the liquid draining into the grates.
Grates may be exposed to a variety of materials which, if allowed to cover their foraminous surfaces, will cause them to clog and cease draining. These materials may include rocks, pebbles, twigs, leaves, paper, dirt, sand, grass, trash or other matter, depending on the grate location. Such a blockage will at best seriously slow down the time required to drain the roof or other surface and the weight of the accumulated water can seriously tax the support structure, possibly resulting in the formation of leaks or even total collapse of the structure.
In order to logically and efficiently remove large amounts of standing water on structures served by drains it is evident that new and improved grate structures must be developed. Further, in order to maintain economy of construction, new and improved grates are needed which are capable of having variable flow rates which can comply with local ordinances governing the flow rate of water input into a storm drain system. Further, these grates must not easily become clogged by debris being washed into them.